The present invention relates to drum bodies with rolling hoops and the process of fabrication of such drum bodies. The drums are provided with at least two rolling hoops, allowing their handling by rolling on a surface, the drum being supported by the rolling hoops.
Drum bodies having at least two rolling hoops with outer diameter greater than that of the drum are already known. These hoops have two main functions, they permit the rolling on a surface of the drum, and they reinforce the structure of the drum by increasing its mechanical strength. Indeed, such a drum must be able to withstand possible deformation or implosion following an impact or contraction due to the heat drop of a product fed into the drum when hot, for example.
However, given that the outer diameter of the hoops is greater than the outer diameter of the drum, such hoops increase the radial bulkiness of the drums. This is a serious inconvenience, especially in the case of the standard 55 gallon drums used worldwide with a capacity of 216.5 liters and a radial spatial requirement standardized at 595.+-.3 mm. The ISO containers which may be used to transport these drums have standard dimensions which are not tailored to accommodate drums. In such situations it is only possible to place three drums with rolling hoops and not four such drums side by side along the width of the container measuring 2334 mm. In these circumstances the container capacity is not used efficiently, the volume being just too small to accommodate a fourth drum. The economy of operation of transporting drums under such conditions is seriously questioned.
Drums provided with depressed corrugations are already known, for example U.S. Pat. No. 1,649,292. The drum disclosed in this patent has corrugations formed within the original diameter of the drum. This drum also has two expanded rolling hoops, adjacent to the corrugations and extending outwards from the drum. The corrugations are intended to reinforce the drum structure in case of shocks. The drum of the U.S. Pat. No. 1,649,292 does not provide a solution to the need to reduce the radial spatial requirement of such drums, since it includes the two widely protruding rolling hoops.
Also, in the German language PCT Application No. WO 85/01714 drums showing different configurations of corrugations are disclosed. As seen from this application the corrugations can be formed within the original diameter of the drum or outside the original diameter. Also, the corrugations can be formed with the peaks outside the diameter of the drum and the troughs inside the diameter. Different combinations of corrugations are shown. A conventional widening of the rolling hoops is disclosed to compensate reduced rolling hoop depth.